Apparatus and methods for synchronization pattern configuration in an optical network

ABSTRACT

Apparatus and methods for discovery, synchronization and operation of network components. In one embodiment, the network comprises a passive optical network (PON), and the components being synchronized include an enhanced OLT (eOLT) and one or more enhanced ONUs (eONUs). The eOLT is configured in one variant to utilize control protocol messaging (such as those used in the MPCP or Multi Point Control Protocol) to communicate particular synchronization parameters and durations to the eONU(s), whether individually or via multicast/broadcast. The synchronization parameter and durations are selected to optimize discovery and synchronization of the eONU(s) with the eOLT, and also optimize (subsequent) normal operation, in one implementation through selection of synchronization patterns which enable most efficient AGC determination, clock recovery (CDR), SBD, and EBD identification.

PRIORITY

This application claims priority to U.S. Provisional Patent ApplicationSer. No. 62/685,793 filed Jun. 15, 2018 of the same title, which isincorporated herein by reference in its entirety.

COPYRIGHT

A portion of the disclosure of this patent document contains materialthat is subject to copyright protection. The copyright owner has noobjection to the facsimile reproduction by anyone of the patent documentor the patent disclosure, as it appears in the Patent and TrademarkOffice patent files or records, but otherwise reserves all copyrightrights whatsoever.

BACKGROUND 1. Technological Field

The present disclosure relates generally to the field of opticalnetworking, and specifically in one aspect, to apparatus and methods forsynchronization configuration within PONs (passive optical networks).

2. Description of Related Technology

Passive optical networks (PONs) are comparatively low-costFiber-to-the-Building/Curb/Home (FTTb, FTTc, FTTh, collectively referredto as FTTx) solutions. A PON is a point-to-multipoint optical networkthat allows service providers to minimize the need for fiber in theoutside portion of the network to interconnect buildings or homes. Thebasic principle of PON, as illustrated in the architecture 100 of FIG.1, is to share the central optical line terminal (OLT) 102 and thefeeder-fiber by as many optical network units (ONUs) 104 as ispractical. This resource sharing allows a significant reduction ofnetwork capital expense allocated to each subscriber and thereforeenables broadband fiber access in areas where achieving profitabilityhas been a formidable task for traditional point-to-point or ring-basedarchitectures.

Various types or variants of PONs exist. For example, those based on theITU-T G.983 standard utilize Asynchronous Transfer Mode (ATM) and aretypically referred to as APON (ATM PON). The final version of ITU-TG.983 is referred to more often as broadband PON, or BPON. A typicalAPON/BPON provides 622 megabits per second (Mbit/s) (OC-12) ofdownstream bandwidth and 155 Mbit/s (OC-3) of upstream traffic, althoughhigher data rates may be accommodated by G.983 systems.

Gigabit Ethernet PON (GPON) provides multiple Layer 2 networks,including: (i) ATM for voice, (ii) Ethernet for data, and (iii) a vendorspecific or proprietary voice data encapsulation protocol. Data rates onthe order of 1.25 Gbit/s to 2.5 Gbit/s downstream and upstream areprovided. However, GPON does not support multicast services, and hencedelivery of Internet Protocol (IP) data is more bandwidth-consuming thanother approaches with multicast.

Additionally, higher data rate system (e.g., those capable of 10 Gbit/sor higher) are already being developed. For instance, so-called XG-PON(10 Gbit/s downstream and 2.5 Gbit/s upstream), specified by ITU G.987,2009, is fundamentally a higher-bandwidth version of GPON. It hassimilar capabilities as GPON and may co-exist on the same fiber.

XGS-PON (10 Gbit/s both downstream and upstream) is specified by ITUG.987.1, 2016. XGS-PON is a higher-bandwidth, symmetric (U/D) version ofGPON. XG-PON1 is specified in ITU G.987.2.

NG-PON2 (10 Gbit/s downstream and upstream, as well as 10 Gbit/sdownstream and 2.5 Gbit/s upstream) is specified under ITU G.989, 2015and enables added capabilities like wavelength mobility and channelaggregation or bonding.

Ethernet PON (1G-EPON) generally delivers 1 Gbit/s symmetricalbandwidth, and uses a Layer 2 network that leverages IP to carry data,voice, and video. Advantageously, EPON equipment does not requiremulti-protocol conversions, and the result is a lower cost ofimplementation (including lower silicon costs) as compared to e.g., GPONdiscussed supra. The higher speed version of EPON is also available(10G-EPON), providing symmetrical bandwidth up to 10 Gbit/s. Even higherdata rate EPON systems will become available in the future, providing 25Gbit/s and 50 Gbit/s symmetric data rates and currently beingstandardized under the IEEE P802.3ca project.

In general, and regardless of the technology/protocol used, PONs aretypically based on a point-to-multipoint (P2MP) passive outside fiberstructure, where the OLT 102 located in the Central Office (CO/hub) ofthe local service provider provides connectivity to a number ofsubscriber equipment modules (ONUs 104), the location of which dependson the deployment scenario.

As the name suggests, the outside fiber plant between the OLT and theONU is completely passive, requiring no power to operate. This reducesany OPEX (operational expense) once the fiber is deployed. Deployment ofthe fiber may be according to any number of layouts, including beingburied underground, placed on aerial poles typically shared with localpower company, or in a mixed scenario, where both underground and aerialdeployment is used to optimize the cost.

So-called “TDMA PON” uses Time Division Multiple Access (TDMA) in theupstream direction, where multiple ONU transmitters are sending data toa single receiver at the OLT, with arbitration between individual ONUscontrolled by the OLT, and individual ONUs being allocated dedicatedtransmission slots (opportunities) in the upstream direction. To achieveTDMA operation in the upstream direction, all ONUs connected to the OLTare temporally synchronized.

Downstream Transmissions

In the downstream direction (i.e., from OLT to ONUs), data frames thatare broadcast by the OLT 102 pass through a single passivesplitter/combiner (PSC), or a cascade of PSCs, to reach the ONUs 104.Each ONU receives part of the transmitted downstream signal. Thedownstream channel properties in this PON system make it a shared mediumnetwork: packets broadcast by the OLT are selectively extracted by thedestination ONU, which applies simple packet-filtering rules such asthose based first on a logical link identifier, and then based on MACaddress. Depending on the underlying PON technology, i.e., whether it isEPON (PON using Ethernet framing, as defined in IEEE Std 802.3), orGPON/XG-EPON/XGS-PON (PON using GEM framing, as defined in a number ofrecommendation series published by ITU-T such as SG15Q2 referencedsupra), the aforementioned logical link identifier can take variousforms. For instance, the logical link identifier may have the form ofthe Logical Link ID (LLID) set forth IEEE Std 802.3 (Clause 65 for1G-EPON, and Clause 76 for 10G-EPON, each incorporated herein byreference in its entirety), another format for GPON, and yet anotherformat for other PON technologies.

FIG. 1 illustrates an example of downstream operation in an extant EPONarchitecture.

Upstream Transmissions

In the upstream direction (see FIG. 2)—i.e., from the ONUs 104 towardsthe OLT 102—any PON looks like a multipoint to point (MP2P) network.Multiple ONUs may transmit simultaneously towards a single receiver atthe OLT. Since the specific PON physical constraints do not allow theONUs to see any data transmissions originating from other subscriberunits, implementation of multiple access/arbitration schemes such asCarrier Sense Multiple Access with Collision Detection (CSMA/CD) is notfeasible. See, e.g., J. Zheng and H. T. Mouftah, “Media Access Controlfor Ethernet Passive Optical Networks: An Overview,” IEEE CommunicationsMagazine, pp. 145-150, 2005, incorporated herein by reference in itsentirety. Obviously, without a centralized form of arbitration,transmissions from individual ONUs would collide at the trunk section ofthe fiber, overlapping and resulting in, inter alia, unrecoverable dataerrors.

ONUs in a typical PON network belong to a single collision domain, andthus a centrally managed channel access is required, such as oneimplemented via TDMA. In such architectures, ONUs in their default stateare not allowed to transmit any data unless a “permissive” event orstate occurs, such as e.g., by being polled specifically by the OLT totransmit. In this way, data collisions are avoided, since the centralOLT controller at any moment of time is aware of the scheduledtransmissions from individual ONUs, such as via the mechanisms of datareporting defined in Multi Point Control Protocol (MPCP) per IEEE Std802.3, previously incorporated herein. Similar mechanisms are alsoimplemented in ITU-T SG15Q2 recommendations for GPON-series PON systems.

In the upstream direction, any existing TDMA PON operates inmultipoint-to-point arrangement, where multiple ONUs transmit towards asingle receiver at the OLT. In such an arrangement, some sort ofarbitration is required to avoid temporal overlap among transmissionsoriginating from individual ONUs. Various arbitration protocols for theupstream direction have been proposed to date, with the time slotted(e.g., TDMA) with scheduling pipelining (similar to IPACT; see“Interleaved Polling with Adaptive Cycle Time (IPACT): Protocol Designand Performance Analysis;” Kramer, G., et al, July 2001, incorporatedherein by reference in its entirety) is used predominantly in commercialproducts. More exotics protocols, relying on modified versions ofEthernet CSMA/CD or CSMA/CA (CSMA with collision avoidance) mechanismshave proven too inefficient to provide SLA (service level agreement)guarantees required for commercial deployments to compete with servicesprovided over P2P or other media.

In the aforementioned default state, the laser in an ONU is turned off.This, inter alia, prevents the generation and accumulation of opticalnoise in the upstream direction. Such optical noise can degrade the OLTreceiver's capability to receive data from more distant ONUs (i.e.,those with weaker signal due to propagation losses), or introduce biterrors into the transmission by degrading the Signal-to-Noise Ratio(SNR).

In an EPON, when a scheduled upstream transmission (time) slot begins,there is some data queued for transmission, and the MPCP (Multi-pointControl Protocol) layer in the ONU starts transmitting data towards thephysical medium. A Data Detector (DD) function in the PON PHY identifiesthe start of the upstream transmission. The Data Detector function (seefor example IEEE Std 802.3, Section 76.3.2.5 for details applicable toEPON) identifies the beginning of the upstream transmission burst, andenables or turns on the ONU laser when the first data block reaches theFIFO delay buffer. Additionally, the Data Detector block adds a certainamount of delay into the transmission path, the delay sufficient toprepare the transmit laser (i.e., turn the transmit laser on, stabilizeits output power, and transmit a synchronization pattern) before theactual queued data is transmitted. This guarantees that the ONU transmitlaser has enough time to reach the optimum operating point andsufficient amount of synchronization pattern is transmitted to aid theoperation of Automatic Gain Control (AGC) and Clock Data Recovery (CDR)blocks in the OLT receive path. While the FIFO buffer contains at leastone data block, the transmit laser in the ONU remains enabled. Similarfunctionality exists in GPON systems as well.

A typical synchronization pattern terminates with a very specificsequence, referred to as the Start-of-Burst delimiter (SBD) or BurstStart (BS) delimiter. The SBD pattern allows the OLT receiver tounequivocally identify the beginning of the FEC (forward errorcorrection)-protected portion of the upstream burst, containing actualqueued data being transmitted by the ONU towards the OLT. The BS patterntypically has specific mathematical properties, allowing the OLTreceiver to detect it with high confidence even in the presence of biterrors introduced by the transmission channel. Only when the last datablock leaves the FIFO buffer, the Data Detector block switches thetransmit laser off, again transmitting the synchronization pattern asthe laser switches off.

Exemplary operation of the Data Detector in the transmit path in the ONU104 is shown in FIG. 3.

The depth of the FIFO buffer within the Data Detector block may beadjusted dynamically to, inter alia, optimize the burst structure andminimize the burst overhead (laser on/off periods, synchronization time,etc.), thereby improving the upstream transmission efficiency.

In the exemplary EPON system, during the MPCP Discovery process, the ONUand OLT negotiate the duration of various burst overhead elements, wherethe OLT announces the minimum required duration of the synchronizationtime (i.e., the Sync Time field in the Discovery GATE MPCPDU, see IEEEStd 802.3, Section 77.3.6.1), and the ONU announces the minimum requiredlaser on and off times (Laser On Time and Laser Off Time fields in theREGISTER_REQ MPCPDU, see IEEE Std 802.3, Section 77.3.6.3). The value ofthese parameters is implementation-dependent, and the negotiationmechanism between the ONU and OLT allows for support of a wide range ofimplementations, as well as mixing ONUs with different hardwarecapabilities connected to one and the same OLT.

The resulting upstream burst structure 400 in 10G-EPON is shown in FIG.4 (individual fields not necessarily to scale), and comprises thefollowing specific fields/areas:

-   -   1. Laser On (402): The ONU transmitter is being switched on and        ramps up towards the optimum operating conditions.    -   2. Sync Time (aka “Burst Preamble”) (404): The ONU transmits        repeatedly the synchronization pattern to aid the operation of        AGC and CDR blocks within the OLT receiver. The BS pattern is        counted as part of the Sync Time block, and designates the end        of the Sync Time and the start of the FEC-protected portion of        the upstream burst. The Sync Time period is used for proper        detection of the incoming data burst, configuration of the gain        unit in the OLT receiver, and clock recovery to synchronize to        the incoming data stream.    -   3. Burst Payload (406): The Burst Payload comprises a series of        FEC codewords, where each codeword comprises FEC payload (actual        user data) and FEC parity (added to improve resilience against        bit errors). The size of the Burst Payload in the exemplary case        of 10G-EPON is an even multiple of the size of the FEC codeword,        since codeword shortening is not supported. A similar situation        takes place in 1G-EPON, where FEC codewords (when FEC is        enabled) are always transmitted as whole. In GPON systems,        upstream burst transmission may be truncated, and individual        data frames fragmented as needed to fit into the allocated        transmission slot.    -   4. Burst End (BE) pattern (408): The BE pattern is used for        signaling the OLT receiver to reset the FEC decoders, and        prepare for the next incoming burst. The BE pattern was used in        the initial implementations of PON burst-mode receivers        (irrespective of the PON type), to give additional time to reset        to the default state. Current implementations largely disregard        the BE presence, and use input power presence as indication to        reset to the default state. Note that the BE pattern is not        FEC-protected, and has properties generally similar to the BS        pattern.    -   5. Laser Off (410): The point where the ONU transmitter laser is        being switched off.        Generally speaking, existing TDMA PON systems (whether specified        in IEEE Std 802.3 or by ITU-T SG15Q2) have fixed Burst Preamble        configuration. During the sync pattern portion of the Burst        Preamble, as discussed supra, the ONU continuously transmits a        pre-selected bit pattern (e.g., a sync pattern of 0×BF 40 18 E5        C5 49 BB 59, as defined in IEEE Std 802.3, subclause 76.3.2.5.2        for 10G-EPON), thereby providing the OLT receiver ability to        perform the AGC (gain control/alignment) and CDR (clock        recovery) functions. In some systems (e.g., 10G-EPON), the        beginning of the data portion of the upstream burst and        terminating with the Burst Preamble (area carrying actual        customer data, with optical FEC protection), is designated with        a specific bit pattern (so-called Start of Burst Delimiter (SBD)        or Start-of-Burst (SOB), depending on the technology; e.g., 0x        6B F8 D8 12 D8 58 E4 AB, as defined in IEEE Std 802.3, subclause        76.3.2.5.2 for 10G-EPON). SBD is selected in a way that meets        specific detection criteria; i.e., it features sufficient number        of 0/1 bit level transitions, it has limited run length (number        of consecutive 0s or 1s), and its Hamming distance from the        background sync pattern is sufficiently large to guarantee        proper detection even in the presence of bit errors in high Bit        Error Ratio (BER) environment. See e.g., Hamming, R. W., “Error        detecting and error correcting codes”. The Bell System Technical        Journal, 29 (2): 147-160 (April 1950), incorporated herein by        reference in its entirety.

Herein lies a salient deficiency with, inter alia, extant PON systems;i.e., the synchronization (e.g., Burst Preamble) structure is fixed,effectively resulting in sub-optimum operation for all OLTs,irrespective of their burst-mode receiver implementation. Accordingly,several operational and implementation optimizations that are notaddressed today are possible, but are precluded through the mandate ofthe fixed, “one size fits all” synchronization structures and protocols.

SUMMARY

The present disclosure addresses the foregoing needs by providing, interalia, methods and apparatus for synchronizing and synchronizationconfiguration within a network such as e.g., a passive optical network(PON).

In a first aspect of the disclosure, a method of operating a passiveoptical network (PON) is described. In one embodiment, the methodincludes: determining a plurality of synchronization parameters to beused during at least two different phases of synchronization between atleast one service node and a controller node of the PON; andtransmitting data indicative of the plurality of synchronizationparameters to the at least one service node via at least one protocoldata message, the at least one protocol data message configured to causethe at least one service node to utilize the plurality ofsynchronization parameters during subsequent discovery orsynchronization process.

In one variant, the at least two different phases comprise: (i) a gainphase relating to signal power transmitted by the at least one servicenode onto the PON; and (ii) a clock signal recovery phase. In anothervariant, the at least two phases further include: (iii) a payload phase.

In one implementation, the payload phase comprises a phase during whichFEC (forward error correction) protected payload data is transmitted,the payload phase delineated by at least two burst delimiter values.

In a further variant, the at least one service node comprises an ONU(optical network unit), and the controller node comprises an OLT(optical line terminal).

In another embodiment, the method of operating a passive optical network(PON) includes: determining at least two sets of synchronizationparameters to be used during respective ones of at least two differentmodes of operation of at least one service node of the PON; andtransmitting data indicative of the at least two sets of synchronizationparameters to the at least one service node via at least one protocoldata message, the at least one protocol data message configured to causethe at least one service node to utilize the at least two sets ofsynchronization parameters during respective ones of: (i) a discoverymode, and (ii) a normal or granting mode.

In yet another embodiment, the method of operating a passive opticalnetwork (PON) includes: determining a plurality of synchronizationparameters to be used by at least one service node of the PON within adynamically variable burst preamble; and transmitting data indicative ofthe plurality of synchronization parameters to the at least one servicenode via at least one protocol data message, the at least one protocoldata message configured to cause the at least one service node to:configure applicable portions of the dynamically variable burst preambleaccording to respective ones of the plurality of synchronizationparameters; and transmit the configured burst preamble to a controllernode of the PON during a discovery or synchronization phase.

In another aspect of the disclosure, an OLT apparatus is disclosed. Inone embodiment, the OLT apparatus includes an enhanced OLT (eOLT)configured to selectively apply synchronization protocols in order tooptimize PON performance. In one variant, the synchronization protocolsare signaled to the various eONU within the network via one or morecontrol messages, and include one or more synchronization patterns forvarious phases of the synchronization and operation modes of the PON.

In another aspect of the disclosure, an ONU apparatus is disclosed. Inone embodiment, the ONU apparatus includes an enhanced ONU (eONU)configured to selectively utilize synchronization protocols signaled bythe cognizant eOLT in order to optimize PON performance.

In a further aspect of the disclosure, an optical network system isdisclosed. In one embodiment, the system includes: (i) one or more eOLTapparatus, and (ii) one or more eONU apparatus in optical communicationwith at least one of the eOLT apparatus.

In a further aspect of the disclosure, a method of synchronization ofcomponents within a network is disclosed. In one embodiment, the networkis an optical network using a TDMA-based protocol, and the methodincludes selectively using synchronization patterns and associated datathat are particularly adapted to particular phases of operation of thesystem components.

In another embodiment, the network is an optical network using anOFDM-based protocol.

In yet another embodiment, the network is an (e.g., differentiallysignaled) electrical PHY network, such as one using a twisted paircabling PHY.

In another aspect, a method of “reusing” allocated space within anexisting protocol message is disclosed. In one embodiment, the methodincludes repurposing bit stuffing or other otherwise non-allocated bitsor fields within the protocol message(s) to signal synchronizationpatterns and related data between an eOLT and one or more eONUs.

In a further aspect, a synchronization protocol is disclosed. In oneembodiment, the protocol is adapted for use in a PON, and includesutilization of one or more control messages configured to cause one ormore recipient entities (e.g., eONUs) to selectively implement one ormore phase-specific synchronization patterns. In one variant, theprotocol utilizes an IEEE Std 802.3-compliant structure.

In yet another aspect of the disclosure, a synchronization data andcontrol message structure is disclosed. In one embodiment, the data andmessage structure comprises inclusion of a plurality of SP_(x)(synchronization pattern) values and associated flags or anotherancillary data relating thereto, transmitted as part of one or morecontrol messages.

In a further aspect, a computer-readable apparatus is disclosed. In oneembodiment, the apparatus includes a storage medium having at least onecomputer program disposed thereon in the form of a plurality ofcomputer-executable instructions. In one variant, the apparatus is ahard disk drive (HDD). In another variant, the apparatus is a solidstate device (SSD). In another variant, the apparatus comprises aprogram memory device.

In another aspect of the disclosure, computerized logic for implementingselective synchronization and operation protocols is disclosed. In oneembodiment, the logic is embodied as software (e.g., one or morecomputer programs). In another embodiment, the logic is embodied asfirmware. In another embodiment, the logic is embodied as part of a FPGAor other gate array. In yet another embodiment, the logic is embodied aspart of an application-specific IC (ASIC).

These and other aspects shall become apparent when considered in lightof the disclosure provided herein.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating an exemplary prior art downstreamchannel transmission process used in EPON applications.

FIG. 2 is a block diagram illustrating an exemplary prior art upstreamchannel transmission process used in EPON applications.

FIG. 3 is a graphical representation of an exemplary prior art datadetector used in EPON applications.

FIG. 4 is a graphical representation of an exemplary prior art upstreamburst structure used in a 10G-EPON applications.

FIG. 5 is a block diagram illustrating an exemplary PON deployment withenhanced ONU (eOLT) and enhanced ONU(s) (eONU(s)), including varioustypes of applications and service domains.

FIG. 6 is a graphical representation of an exemplary embodiment of anupstream burst structure according to the present disclosure.

FIG. 7 is a logical flow diagram illustrating one embodiment of ageneralized method for eONU discovery and synchronization by an eOLTwithin a PON, according to the disclosure.

FIG. 7A is a logical flow diagram illustrating one implementation of themethod of FIG. 7.

FIG. 7B is a logical flow diagram illustrating another implementation ofthe method of FIG. 7.

FIG. 8 is a logical flow diagram illustrating one embodiment of ageneralized method for eONU discovery and synchronization by anunregistered eONU within a PON, according to the present disclosure.

FIG. 9 is a functional block diagram of one embodiment of an eOLTapparatus for use in a PON, according to the present disclosure.

FIG. 10 is a functional block diagram of one embodiment of an eONUapparatus for use in a PON, according to the present disclosure.

FIG. 11 is a tabular representation of an exemplary embodiment of aprotocol control message for use in a next generation PON (NG-PON),according to the present disclosure.

All figures © Copyright 2018 Charter Communications Operating, LLC. Allrights reserved.

DETAILED DESCRIPTION

Reference is now made to the drawings wherein like numerals refer tolike parts throughout.

As used herein, the term “application” refers generally and withoutlimitation to a unit of executable software that implements a certainfunctionality or theme. The themes of applications vary broadly acrossany number of disciplines and functions (such as on-demand contentmanagement, e-commerce transactions, brokerage transactions, homeentertainment, calculator etc.), and one application may have more thanone theme. The unit of executable software generally runs in apredetermined environment; for example, the unit could include adownloadable Java Xlet™ that runs within the JavaTV™ environment.

As used herein, the term “client device” includes, but is not limitedto, set-top boxes (e.g., DSTBs), gateways, modems, personal computers(PCs), and minicomputers, whether desktop, laptop, or otherwise, andmobile devices such as handheld computers, PDAs, personal media devices(PMDs), tablets, “phablets”, and smartphones.

As used herein, the term “computer program” or “software” is meant toinclude any sequence or human or machine cognizable steps which performa function. Such program may be rendered in virtually any programminglanguage or environment including, for example, C/C++, Fortran, COBOL,PASCAL, Python, assembly language, markup languages (e.g., HTML, SGML,XML, VoXML), and the like, as well as object-oriented environments suchas the Common Object Request Broker Architecture (CORBA), Java™(including J2ME, Java Beans, etc.) and the like.

The term “Customer Premises Equipment (CPE)” refers without limitationto any type of electronic equipment located within a customer's orsubscriber's premises and connected to or in communication with anetwork.

As used herein, the terms “Internet” and “internet” are usedinterchangeably to refer to inter-networks including, withoutlimitation, the Internet.

As used herein, the term “memory” includes any type of integratedcircuit or other storage device adapted for storing digital dataincluding, without limitation, ROM. PROM, EEPROM, DRAM, SDRAM, DDR/2SDRAM, GDDRx, EDO/FPMS, RLDRAM, SRAM, “flash” memory (e.g., NAND/NOR),3D memory, and PSRAM.

As used herein, the terms “microprocessor” and “processor” or “digitalprocessor” are meant generally to include all types of digitalprocessing devices including, without limitation, digital signalprocessors (DSPs), reduced instruction set computers (RISC),general-purpose (CISC) processors, microprocessors, gate arrays (e.g.,FPGAs), PLDs, reconfigurable computer fabrics (RCFs), array processors,secure microprocessors, and application-specific integrated circuits(ASICs). Such digital processors may be contained on a single unitary ICdie, or distributed across multiple components.

As used herein, the terms “MSO” or “multiple systems operator” refer toa cable, satellite, or terrestrial network provider havinginfrastructure required to deliver services including programming anddata over those mediums.

As used herein, the terms “network” and “bearer network” refer generallyto any type of telecommunications or data network including, withoutlimitation, optical networks (such as PONs), hybrid fiber coax (HFC)networks, satellite networks, telco networks, and data networks(including MANs, WANs, LANs, WLANs, internets, and intranets). Suchnetworks or portions thereof may utilize any one or more differenttopologies (e.g., ring, bus, star, loop, etc.), transmission media(e.g., optical fiber, wired/RF cable, RF wireless, millimeter wave,etc.) and/or communications or networking protocols (e.g., SONET,DOCSIS, IEEE Std 802.3, ATM, X.25, Frame Relay, 3GPP, 3GPP2, WAP, SIP,UDP, FTP, RTP/RTCP, TCP/IP, H.323, etc.).

As used herein, the term “network interface” refers to any signal ordata interface with a component or network including, withoutlimitation, those of the FireWire (e.g., FW400, FW800, etc.),Thunderbolt, USB (e.g., USB2.0, USB 3.0, etc.), Ethernet (e.g., 10/100,10/100/1000 (Gigabit Ethernet), 10-Gig-E, etc.), MoCA, Coaxsys (e.g.,TVnet™), radio frequency tuner (e.g., in-band or OOB, cable modem,etc.), Wi-Fi (802.11), WiMAX (802.16), Zigbee®, Z-wave, PAN (e.g.,802.15), power line carrier (PLC), or IrDA families.

As used herein, the term “server” refers to any computerized component,system or entity regardless of form which is adapted to provide data,files, applications, content, or other services to one or more otherdevices or entities on a computer network.

As used herein, the term “storage” refers to without limitation computerhard drives, SSDs, DVR devices, flash drives, memory, RAID devices orarrays, optical media (e.g., CD-ROMs, Laserdiscs, Blu-Ray, etc.), or anyother devices or media capable of storing content or other information.

As used herein, the term “Wi-Fi” refers to, without limitation, any ofthe variants of IEEE-Std 802.11 or related standards including 802.11a/b/g/n/s/v/ac or 802.11-2012.

As used herein, the term “wireless” means any wireless signal, data,communication, or other interface including without limitation Wi-Fi,Bluetooth, 3G (3GPP/3GPP2), HSDPA/HSUPA, TDMA, CDMA (e.g., IS-95A,WCDMA, etc.), FHSS, DSSS, GSM, PAN/802.15, WiMAX (802.16), 802.20,Zigbee®, Z-wave, narrowband/FDMA, OFDM, PCS/DCS, LTE/LTE-A, analogcellular, CDPD, satellite systems, millimeter wave or microwave systems,acoustic, and infrared (i.e., IrDA).

Overview

As previously noted, current synchronization operations in e.g., PONsare not optimized in a variety of aspects, including notably use ofcommon synchronizing patterns for various phases of synchronization, andvarious types of operation of ONUs/OLTs.

In contrast, the inventors of the present disclosure have conceptuallyrecognized that, in certain e.g., OLT receiver implementations, it wouldbe beneficial for the AGC and CDR periods to have different bitpatterns, for instance where one pattern is optimized for a firstparameter or consideration (such as quick gain control adjustment), andanother one optimized for a second parameter or consideration (e.g.,quick clock recovery). In the exemplary case of the OLT burst modereceiver, during the AGC period, the receiver is ideally provided asmany “1s” as possible, to reliably measure the power of the incomingsignal. Conversely, during the CDR period, the OLT burst mode receiveris ideally provided with as many data value transitions (e.g., between 0and 1) as possible to reliably detect and align to the phase of theincoming signal. As such, the requirements for AGC and CDR periods arecontradictory, and cannot be optimized with a single bit pattern.

When AGC and CDR bit patterns are optimized for performance, the SBDpattern must still meet the detection requirements criteria for both theAGC and CDR patterns.

Additionally, in certain implementations, different AGC, CDR, and SBDpatterns may be utilized during the discovery (e.g., ONU detection andregistration) versus the normal operation modes, again optimizing theresulting system performance. Specifically, during the discoveryoperation, the OLT does not have any information (or has incompleteinformation) about the newly registering ONU, and may require longer,more bit-error tolerant AGC, CDR, and/or SBD patterns, to facilitatequicker and more reliable ONU discovery. During the normal operation,once the ONU capabilities and transmission profile are known to the OLT,the AGC period duration can be minimized (the OLT already knows withreasonable approximation at what power level the ONU is transmitting).Similarly, during such normal operation, the CDR period can beshortened.

Accordingly, exemplary embodiments of the enhanced OLT (eOLT) and(enhanced ONU (eONU) described herein allow for variation of the bitpattern in e.g., the specific Burst Preamble periods, to optimize eOLTdetection and reception (in addition to or alternatively with the use ofmodified length) capability. The eOLT can optionally announce differentbit patterns for specific operation modes (including different bitpattern value as well as their duration), advantageously allowing forfurther optimization of burst detection, as well as increases inupstream transmission efficiency.

Detailed Description of Exemplary Embodiments

Exemplary embodiments of the apparatus and methods of the presentdisclosure are now described in detail. While these exemplaryembodiments are described primarily in the context of an optical network(e.g., PON) architecture having a network operator, digital networkingcapability, IP delivery capability, and a plurality of premises clientdevices/CPE, the general principles and advantages of the disclosure maybe extended to other types of networks and architectures that areconfigured to deliver digital e.g., media data (e.g., text, video,and/or audio) or other data. Such other networks or architectures may bebroadband, narrowband, wired, or otherwise, the following thereforebeing merely exemplary in nature.

It will also be appreciated that while various embodiments or aspectsdiscussed herein are described in the context of next generation EPONsystem (referred to herein as “NG-EPON”) currently under development inthe IEEE P802.3ca project, the various features and functionalitiesdescribed can be readily adapted by those of ordinary skill, when giventhis disclosure, to any type of PON system, defined by any standarddevelopment organization, vendor, etc., and in fact other types of PHYsand/or modulation schemes as referenced elsewhere herein.

Moreover, the disclosed aspects and functionality are in no way limitedto PON systems; other types of PHY including for example wired systems(e.g., twisted pair systems utilizing differential signaling) may alsobenefit from the various aspects disclosed herein.

It will further be appreciated that while described generally in thecontext of a network providing FTTx distribution services to users orsubscribers of the commercial PON-based network referenced above fore.g., Internet data or backhaul services, the present disclosure may bereadily adapted to other types of environments including, e.g.,commercial/enterprise, and government/military applications, and/orother types of internetworks. Myriad other applications are possible.

While the terms “downstream” and “upstream” and “ingress” and “egress”are used with reference to the various functions of the nodes describedherein, it should be appreciated that such usage is provided solely forclarity, and is not in any way determinative or dispositive of alocation or other attribute of a component, system or process. In fact,it is readily appreciated that typical nodes, applications, and/ortransactions are bidirectional in nature, and thus nodes may possessboth downstream/upstream and/or ingress/egress capabilities.

Lastly, it is noted that while a certain scheme or model (e.g., OSImodel, Layers 1, 2, 3, etc.) for network layering or construction arereferenced herein, the various aspects of the disclosure are in no waylimited to such descriptions, models or schemes.

Other features and advantages of the present disclosure will immediatelybe recognized by persons of ordinary skill in the art with reference tothe attached drawings and detailed description of exemplary embodimentsas given below.

Service Provider Network—

FIG. 5 illustrates an exemplary deployment architecture 500 for thevarious optimization-capable entities described subsequently herein(i.e., OLT, ONU, and network logic servers or processes), includingvarious use cases/scenarios. As shown in FIG. 5, the architecturecomprises an eOLT 502 which is optically coupled with a number of eONUs504 a-504 f used with various types of premises and/or applications,including for MTU (multi-tenant unit) delivery 504 a, 504 b, cellularbase station backhaul 504 c, enterprise or business services delivery504 d, consumer (e.g., home or apartment) service provision 504 f, etc.As indicated, various “last mile” portions or technologies may be used,including FTTH (fiber to the home), FTTC/FTTN (fiber to the curb/node),FTTB (fiber to the building), as well as the illustrated MTU deliveryconfigurations.

As described in greater detail below with respect to FIGS. 6-10, theenhanced OLTs 502 and enhanced ONUs 504 a-504 f of the exemplaryillustrated embodiment include functionality to enable optimization ofthe timing and/or power synchronization processes. It will beappreciated that while the architecture 500 of FIG. 5 is illustrated ashaving all eONUs 504 (as opposed to unenhanced or prior art ONUs, notshown), the architecture 500 can be configured to accommodate aheterogeneous mix of eONUs and ONUs, such as during a “phased”introduction or deployment of the eONUs. In one such configuration, theprotocols (described in detail below) used by the eOLT 502 may simply beduplicated; i.e., the eOLT can be configured to use both prior artprotocols for interaction with the ONUs, and the enhanced protocolsdescribed herein for communication with the eONUs 504, including instaggered, time-divided, frequency/wavelength-divided, or other multipleaccess schemes, whether during the discovery phase or otherwise.

Synchronization Protocol—

Exemplary implementations of the synchronization protocols of thedisclosure are now described in detail. It is noted that the followinghigh-level protocol description is described in a PON-versionindependent manner; i.e., is not specific to particular EPON or GPONprotocols, messages, etc. Implementation examples for NG-EPON, usingEPON-specific protocols, message definitions, etc. are providedsubsequently herein.

Generally speaking, the disclosed exemplary embodiments of thesynchronization protocol (as applied to PONs) provide one or more of thefollowing functionalities, depending on the particular implementation:

-   -   (i) The ability to announce a selected or proposed AGC pattern,        optimized for the given OLT burst-mode receiver implementation,        to at least one of the connected ONUs. Several related scenarios        are possible, including for example (a) use of a broadcast        announcement to all connected ONUs; (b) multicast announcement        to a selected group or subset of connected ONUs; and (c) unicast        announcement to one ONU (or one ONU at a time, according to a        sequence or prescribed order).    -   (ii) The ability to announce a selected or proposed CDR pattern,        optimized for the given OLT burst-mode receiver implementation,        to at least one of the connected ONUs. Several related scenarios        are possible, including for example (a) use of a broadcast        announcement to all connected ONUs; (b) multicast announcement        to a selected group or subset of connected ONUs; and (c) unicast        announcement to one ONU (or one ONU at a time, according to a        sequence or prescribed order).    -   (iii) The ability to announce a selected or proposed SBD        pattern, optimized for the given OLT burst-mode receiver        implementation, to at least one of the connected ONUs. Several        related scenarios are possible, including for example (a) use of        a broadcast announcement to all connected ONUs; (b) multicast        announcement to a selected group or subset of connected ONUs;        and (c) unicast announcement to one ONU (or one ONU at a time,        according to a sequence or prescribed order).    -   (iv) The ability to announce a selected or proposed EBD (end of        burst) pattern, optimized for the given OLT burst-mode receiver        implementation, to at least one of the connected ONUs. Several        related scenarios are possible, including for example (a) use of        a broadcast announcement to all connected ONUs; (b) multicast        announcement to a selected group or subset of connected ONUs;        and (c) unicast announcement to one ONU (or one ONU at a time,        according to a sequence or prescribed order).    -   (v) The ability to announce selected or proposed different AGC,        CDR, SBD and/or EBD pattern values for the discovery operation        (when individual ONUs are discovered and first registered) and        normal granting operation (when individual ONUs have been        already registered and are polled periodically for transmission        of queued used data). Several related scenarios are possible,        including for example (a) use of a broadcast announcement to all        connected ONUs; (b) multicast announcement to a selected group        or subset of connected ONUs; and (c) unicast announcement to one        ONU (or one ONU at a time, according to a sequence or prescribed        order).    -   (vi) The ability to announce selected or proposed durations of        AGC, CDR, SBD and/or EBD pattern values for the discovery        operation (when individual ONUs are discovered and first        registered) and normal granting operation (when individual ONUs        have been already registered and are polled periodically for        transmission of queued used data). Several related scenarios are        possible, including for example (a) use of a broadcast        announcement to all connected ONUs; (b) multicast announcement        to a selected group or subset of connected ONUs; and (c) unicast        announcement to one ONU (or one ONU at a time, according to a        sequence or prescribed order).    -   (vii) The ability to combine AGC and CDR periods, as needed,        into a single pattern announcement, through the announcement of        the same pattern during the AGC and CDR announcement, or        alternatively—through the use of two announcement (one for AGC        and CDR, and one for SBD), or alternatively three discrete        announcement messages (one for AGC, one for CDR, and one for        SBD).

FIG. 6 illustrates one embodiment of an upstream burst structureaccording to the present disclosure. As previously noted, in theexemplary case of an eOLT burst mode receiver, during the AGC period,the receiver is ideally provided as many data “1s” as possible, toreliably measure the power of the incoming signal (i.e., transmittedfrom the eONU). Conversely, during the CDR period, the eOLT burst modereceiver is ideally provided with as many data value transitions (e.g.,between 0 and 1) as possible to reliably detect and align to the phaseof the incoming signal. As such, the requirements for AGC and CDRperiods are contradictory, and cannot be optimized with a single bitpattern.

Moreover, patterns for periods of discovery of e.g., unregistered eONUsby the eOLT may not be optimized for periods of normal (granting)operation; i.e., when the ONU has been registered and subsequently wantsto transmit data upstream to the OLT during is assigned TDMA slot (orOFDM time/frequency resource block, as discussed in greater detailelsewhere herein).

Accordingly the exemplary structure of FIG. 6 advantageously addressesthese issues by, inter alia, enabling the burst preamble used by theenhanced ONU (eONU) to be dynamically varied as a function of one ormore parameters; e.g., time and/or operational mode. Specifically, theburst structure 600 of FIG. 6 explicitly defines four areas (portions)of the upstream burst; i.e., SP₁ 602, SP₂ 604, SP₃ 606, and TP 608. Inone variant, the size of each upstream burst area is expressed asinteger multiples of a prescribed primary data block size (i.e., 2×N,3×N, etc., where N=the prescribed block size). For example, in the caseof NG-EPON defined under the incipient IEEE P802.3ca project standard,the data block size would be equal to 257-bits, resulting from the256b/257b line code selected for the use in this particular system. Inother systems, the data block size might be different, depending on anynumber of factors including the line code used (e.g., 8B10B vs.256b/257b).

The above-referenced four separate regions 602, 604, 606, 608 of the FECunprotected area 609 of the upstream burst structure 600 include: (1)Sync Pattern SP₁ period 602, covering the laser on (T_(on)) zone 615 andgain control adjustment (T_(rsettling)) zone 616; (2) Sync Pattern SP₂period 604, covering the clock recovery period (T_(CDR)) zone 618; (3)Sync Pattern SP₃ period 606, covering the start of burst delimiter (SBD)619; and (4) Terminating Pattern TP period 608, covering the end ofburst delimiter (EBD) 620.

The FEC protected area 610 includes in the illustrated embodiment aplurality of FEC (forward error correction) codewords 612, althoughother configurations may be utilized consistent with the disclosedprotocol.

The values as well as durations for SP₁, SP₂, SP₃, and/or TP periods areannounced in one embodiment by the eOLT 502 to at least one of theconnected eONUs 504. As noted supra, several scenarios are possible,including for instance broadcast announced to all eONUs, multicastannouncement to a selected group of connected eONUs, and unicastannouncement to one eONU at a time. The broadcast announcement istypically used for example when targeting all eONUs during the discoveryprocess. The unicast announcement is typically used for example whentargeting one specific eONU requiring a change of any of the SP₁, SP₂,SP₃, and/or TP parameters. Finally, the multicast announcement istypically used for example when targeting a specific group of connectedeONUs (for example, all eONUs from a specific manufacturer, all eONUsthat are at a specific distance from the OLT, all eONUs within aprescribed portion of the fiber architecture 500, all eONUs within aprescribed range of network addresses, etc.).

During the discovery operation, the eOLT 502 broadcasts the values ofSP₁, SP₂, SP₃, and/or TP patterns 602, 604, 606, 608 to all unregisteredeONUs, using specific control messages (referred hereinafter to asSP_VALUE). The structure, size, and bit encoding of SP_VALUE messagesare PON-system specific, but the SP_VALUE generally includes at leastthe following information:

(i) A Pattern Identifier or PI (SP₁, SP₂, SP₃, TP), expressed in oneimplementation in the form of an explicit identifier (alphanumeric) orindex in a message sequence.

(ii) An expected number of messages in the sequence (EN), with aplurality of possible values (discussed below in greater detail). When amessage with an unexpected number of messages in the sequence isreceived, the eONU implements a prescribed error or remediation action;e.g., it ignores such SP_VALUE and information contained therein.

In one variant, the expected number of messages parameter is set to 2,and the TP 608 is not announced, the SP₁ 602 and SP₂ 604 are combinedinto a single Burst Preamble zone and announced using a single message(first of the two messages), and SP₃ 606 is announced separately (secondof the two messages).

In another variant, the expected number is set to 3, and the TP 608 isnot announced, with SP₁ 602, SP₂ 604, and SP₃ 606 being all announcedseparately via three (3) respective messages.

In another variant, the expected number is set to 3, and the TP 608 isannounced (first message), SP₁ 602 and SP₂ 604 are combined into asingle Burst Preamble zone and announced using a single (second)message, and SP₃ 606 is announced separately (third message).

Lastly, in a further variant, the expected number is set to 4, and theTP 602, SP₁ 604, SP₂ 606, and SP₃ 608 are all announced separately viafour respective messages.

(iii) A Pattern Value (PV), comprising an actual bit pattern value forthe given Burst Preamble zone carried in the given SP_VALUE message.

(iv) A Balanced Flag (BF), used for signaling desired SP_(x) value(s),where x=1, 2 . . . n. For instance, in one variant, if BF is set (true),rather than repeating SPx+SPx . . . SPx N times, the receiving eONU 504alternates SPx and its inverted value (!SP_(x)) N times; i.e., transmitthe following sequence: SPx+!SPx+SPx+ . . . +!SPx. If reset (false), thereceiving eONU transmits a simple sequence of SP values, such as thefollowing: SPx+SPx+SPx+ . . . +SPx.

(v) A Reversed Flag (RF), used in conjunction with the BF for signalingdesired SPx value(s). In one variant, if the RF is set (true), ratherthan repeating SPx+SPx . . . SPx N times, the receiving eONU alternatesSPx and its reversed value (˜SPx) N times; i.e., transmit the followingsequence SPx+˜SPx+SPx+ . . . +˜SPx. If reset (false), the eONU transmitsa simple sequence of SP values, such as the following: SPx+SPx+SPx+ . .. +SPx. The Balanced Flag and Reversed Flag are mutually exclusive;i.e., when the Balanced Flag is set, the Reversed Flag shall be reset,and vice versa.

Note that depending on the size of available control messages in thegiven PON system in which the protocol is being utilized, the SP_VALUEmay be encoded into a single message carrying all target values of SP₁,SP₂, SP₃, and/or TP patterns 602, 604, 606, 608, together with theassociated set (AS) of data. In one variant, the AS includes thefollowing information: (1) the pattern identifier (PI), (2) the expectednumber (EN), (3) the balanced flag (BF), and (4) the reversed flag (RF),where each value of SP₁, SP₂, SP₃, and/or TP patterns includes thisassociated information set.

Alternatively, the SP_VALUE may be encoded into a number of messages,where each message carries only one value of SP₁, SP₂, SP₃, and/or TPpatterns 602, 604, 606, 608, together with the associated set (AS).

It will be appreciated that based on the particular implementation(including protocol limitations associated therewith), variouscombinations of the foregoing can be used consistent with the presentdisclosure. For example, as noted above, a single message with fourpatterns, plus associated set, can be utilized. Alternatively, each ofthe patterns can have their own associated set or sets. In the exemplarycase of EPON for instance, a control message is 64B wide, and cansupport just one pattern and one set of control flags therein. Hence,each SP_(x) value requires a separate message. In other implementations,a single control message may carry all SP_(x) values and associatedflags (whether the associated flags are applicable to all SP_(x) valuesor only individual ones thereof), provided that enough space isavailable. Yet other combinations will be appreciated by those ofordinary skill given the present disclosure, consistent with theparticular limitations of the prevailing protocol(s).

Apart from the target values of SP₁, SP₂, SP₃, and/or TP patterns, theeOLT 502 also notifies at least one connected eONU of the duration ofthe given pattern to be used during the prescribed operations or modesof interest. These duration values associated with each pattern arevendor-specific, and depend on the particular eOLT burst-mode receiverimplementation. For example, in one variant, the operations/modesinclude: (i) the discovery operation, and (ii) normal (granting)operation. In one implementation, the duration of the given pattern isexpressed in multiples of the pattern size (data block). For example, inNG-EPON the data block is equal to 257 bits, and hence the duration ofeach pattern is expressed in integer multiples of 257 bits (i.e., 257bits, 514 bits, 771 bits, etc.). Similar logic applies to other linecodes (e.g., 8B/10Bm 64B/66B, etc.).

In one embodiment, the eOLT 502 announces the aforementioned targetpattern durations using a single SP_DURATION message, the lattercontaining target pattern durations for each pattern for both (i) thediscovery operation, and (ii) the normal (granting) operation. Otheroperations/modes can be added; e.g., a “test” mode or the like, suchadditional operation/mode being serviced by the same message (withadditional pattern duration values applicable to the addedoperation/mode in one embodiment).

Alternatively, the eOLT may announce target pattern durations using morethan one message; i.e., one for each operation/mode being configured.For example, in one scenario, two (2) SP_DURATION messages are used, onecarrying only target pattern durations for each pattern for theabove-described discovery operation (mode) only, and a second onecarrying target pattern durations for each pattern for the normal(granting) operation/mode only. Other operations/modes can be added;e.g., the aforementioned “test” mode or the like, such additionaloperation/mode being serviced by a separate message in one embodiment.

Moreover, in other embodiments, all or portions of the SP_DURATION datamay be carried in dedicated control messages, or added into one or moreexisting control messages provided that sufficient space within themessage is available.

In operation, the eONU 504 keeps track of the individual announcedpattern values and their respective durations, as announced by the eOLT502. For instance, in one variant, the eONU assembles a data structure(e.g., table, relational database file, etc.) which correlates thesevalues and enables access thereto by the eONU logic 1011 (see FIG. 10).In one embodiment, the eONU is configured such that, without a completeset of the pattern values and their respective durations, the eONU willnot attempt registration; i.e., the eONU 504 ignores all opportunitiesfor registration until a complete set of pattern values and theirrespective durations is received from the eOLT, such as via the SP_VALUEand SP_DURATION messages discussed above.

Moreover, in one variant, the eONU logic is configured such that onceregistration has been successfully completed, the eONU 504 ignores allsubsequent SP_VALUE and SP_DURATION messages associated with thediscovery operation (mode), but receives and processes all SP_VALUE andSP_DURATION messages associated with the normal (granting) operation ormode. This logic allows the eOLT 502 to, inter alia, modify data such asthe pattern values and/or their duration, for a specific eONU in atargeted fashion. This functionality advantageously provides anopportunity to further optimize the eONU burst structure, and receptionof the upstream data burst generated by the given eONU.

In one embodiment, the eONU 504 is further configured to purge allstored pattern values and their respective durations on local and/orremote deregistration. Additionally, the eONU is configured to discardany received SP_VALUE and SP_DURATION messages containing invalidpattern indices; e.g., when only 3 pattern values are expected, but theOLT announced pattern number is 5. This prevents the eONU from storingand acting on invalid information received from the eOLT 502. In onevariant, the eONU is restricted to performance of validation of patternvalues and their respective durations, as received from the eOLT,according to the foregoing logic. This in effect means that the eONUputs explicit “trust” in the values announced by the eOLT, as long asthe received data set is complete. In the exemplary system architecture,the eOLT 502 is the only device with visibility into the complete PON500, all connected eONUs 504, signal quality, and further has sufficientinformation to make decisions on any adjustments to the pattern valuesand/or their respective durations for particular eONUs 504.

Methods—

FIG. 7 illustrates one embodiment of a generalized method for eONUdiscovery and synchronization by an eOLT within a PON, according to thedisclosure.

As shown, the method 700 begins with the eOLT initiating discovery ofthe one or more eONUs (step 702). This initiation may be for example asa result of an eOLT startup or reboot, system configuration changes(e.g., addition of nodes or eONUs, etc.), periodic refresh, or inresponse to an operator command or recovery from an error event.

Next, at step 704, the eOLT selects the discovery mode configuration forthe eONUs. As described in greater detail below, this may include forexample selection of the SP₁-SP₃ and TP parameters, as well asduration(s) applicable thereto and the associated data such as BF, RF,etc. This selection may be “blind” (i.e., where the eOLT has no a prioriknowledge regarding the eONU configuration, laser, etc., such as forunregistered eONUs), or based on prior data obtained by the eOLTregarding the (given) eONU (e.g., previously registered). As such, theeOLT may simply select a default set of parameters to communicate to theeONUs, with the default being selected for example to optimizesynchronization across a plurality of possible eONU types andconfigurations.

At step 706, the eOLT transmits the data relating to the selectedparameters to the relevant eONUs via an interposed PHY. As previouslyindicated, the transmission may be in the form of a broadcast (such thatall eONUs on the PON receive the data), or multicast (subset of eONUs),or one or more unicasts (to one or more particular eONUs only) accordingto the underlying communication protocol used (see also FIG. 7a ,discussed below). For instance, the communication protocol may comprisean IEEE Std 802.3-based protocol (Ethernet), and the PHY may compriseany available PHY suitable for transmitting the messages and to whichthe target eONUs have access, such as e.g., the optical PHY itself,wired CAT-5/6, wireless interface, etc. The aforementioned PON-specificcontrol messages (e.g., SP_VALUE and SP_DURATION) are be used as thebasis for these messages in one embodiment.

At step 708, the eOLT determines whether the target eONUs have respondedto the transmitted (control) messages. In one simple model, an ACK orother protocol mechanism is used to confirm message receipt via thecontrol channel, e.g. Multi Point Control Protocol (MPCP) in the case ofEthernet PON. Alternatively (or in conjunction with the foregoing)reception of optical domain synchronization signals generated by theeONU(s); i.e., the eONU turning its laser on and initiating the PONsynchronization protocol, can be used as the basis of determiningreception of the transmitted messages. In the case where the opticalsynchronization signals are used as a basis for determining reception,and no optical signal is present from the target eONUs, severalscenarios are possible; i.e., the target eONU(s) (i) may not havereceived the transmission for whatever reason (wrong address,transmission medium errors, etc.), or (ii) did receive the data, but thedata is incomplete or cannot otherwise be validated or utilized (e.g.,the expected number or EN is not the same as the number actuallyreceived). In such cases, the eOLT will “adjust” the data transmission(step 709) whether by re-transmitting the data/messages as originallysent, utilizing another protocol or PHY to communicate with the eOLT,changing the number or format of protocol messages used (e.g., selectinganother of the 2, 3, or 4 message (EN) SP_VALUE protocols discussedabove), or otherwise.

It will also be appreciated that error messages issued by the receivingeONU, such as upon failure to validate the transmitted control messages,may be used at all or part of the basis of this step 708 logic. See thediscussion of FIG. 8 below.

When the appropriate optical synchronization signals are present fromthe target eONUs (as configured by the data sent via the one or moremessages) per step 708, the eOLT next processes the received eONUtransmissions per step 710. In one embodiment, this processing includesutilization of the AGC, CDR, SBD, and EBD patterns dictated by the eOLT,so as to achieve the desired functions; i.e., gain adjustment, clockrecovery, FEC codeword start/finish delineation, etc. Per step 712, ifan update to one or more of the parameters is required (e.g., where theeOLT cannot conduct successful clock recovery based on the transmittedpattern), new or updated data is sent to the affected eONU(s) per step714, and the synchronization re-attempted.

Assuming successful synchronization (and hence completion of thediscovery mode), the eOLT then selects the normal (granting) operationalconfiguration(s) for the target eONU(s) per step 716, and transmitsthese data to the target eONU(s) per step 718, such as via theaforementioned SP_VALUE and SP_DURATION messages particular to theoperational mode. Note that the selected normal (granting) operationalmode parameters, as discussed elsewhere herein, will typically bedifferent than those selected for the discovery/synchronization mode, soas to optimize performance of the PON.

Moreover, it will be recognized that the selection of the normaloperational mode parameters may occur contemporaneously with selectionof discovery mode parameters (e.g., at step 704), or elsewhere duringthe method 700. For example, as discussed above, the discovery andoperational mode parameters/duration values may be aggregated into oneor more SP_VALUE and/or SP_DURATION control messages). In some variants,selection of the operational mode parameters is predicated or based atleast partly on the discovery mode parameters selected. Yet further, thepresent disclosure contemplates that the processing of the received eONUoptical transmissions at step 710 by the eOLT logic may include analysisthat is used to inform the selection of the normal operational modeparameters; e.g., based on observed characteristics of the discoverysignal transmissions from the eONU(s) as received by the eOLT receiver.

It will also be appreciated that the PHY used for transmission of thenormal operational mode data messages may be a different one than thatinitially used to transmit the discovery mode data messages. Forexample, after successful synchronization, the eOLT and eONU arecommunicative via the optical domain, and hence data may be transmittedvia the PON fiber.

FIG. 7A illustrates one implementation of the method 700, particularlystep 705 thereof. As shown, in the exemplary implementation, the eOLTfirst selects a desired target population of eONUs within the PON toconfigure per step 720. This selection may be based on for exampleknowledge of the PON configuration (e.g., via access to a database ordata structure indicating eONU membership and network address for thePON).

Per step 722, the eOLT then selects the discovery mode burst structureparameters for the target eONU(s); i.e., SP₁-SP₃, and TP. Per step 724,the corresponding durations (e.g., integer multiples of the line code)are selected for use with the various burst parameters as previouslydescribed.

Lastly, per step 726, the eOLT transmits the selected parameters andduration values to the target eONU(s) via one or more protocol (e.g.,control) messages, as described elsewhere herein.

FIG. 7B illustrates one implementation of the method 700, particularlystep 715 thereof. As shown, in the exemplary implementation, the eOLTfirst attempts to synchronize with a given eONU during a prescribed timeslot per step 730. The synchronization includes in the exemplaryembodiment receipt of the AGC, CDR, SBD and EBD “training” patternstransmitted from the eONU during the TDMA slot.

Per step 732, the eOLT then determines whether the synchronization(discovery) process was successful. If successful, the method 700proceeds to the operational mode parameter selection of step 716. Innot, the per step 734, the eOLT logic identifies the failed portion ofthe synchronization process (e.g., the clock could not be recovered fromthe CDR pattern), and an updated value of that parameter selected andtransmitted to the relevant eOLT (e.g., via one or more additionalcontrol messages) per step 736.

Referring now to FIG. 8, one embodiment of a generalized method for eONUdiscovery and synchronization by an unregistered eONU within a PON isshown and described.

As shown, the method 800 begins with the eONU laser being held in an“off” or standby mode per step 802. As previously noted, suchoff/standby operation minimizes the introduction of optical noise ontothe PHY during periods of non-use (non-access) of the PHY by thatparticular eONU.

Thereafter, per step 804, the eONU receives the discovery mode datatransmitted by the eOLT (such as via the control message(s)). Aspreviously described, this data is transmitted in one embodiment via aseries of control messages sent by the cognizant eOLT to the eONU(s).

Per step 806, the received messages are then validated against one ormore criteria. In one implementation, this validation includes checkingthe EN value to determine whether the number of messages receivedmatches that value. Additional validation criteria may be used as well,such as for example whether the transmitted pattern values are withinprescribed limits or formats, whether the overall length of themessage(s) is proper, etc.

If validation of step 806 is successful at step 810, then per step 812,the eONU updates its stored configuration data with the transmittedsynchronization parameters, and then initiates the synchronizationprotocol via the eONU laser, using the updated parameters (assuming noother preconditions are outstanding) per step 814.

Alternatively, if the validation of the control messages from the eOLTis not successful per step 810, the eONU logic ignores the message(s),performs no update, and issues an error message or flag. In one variant,this error message comprises another protocol (e.g., 802.3) controlmessage that is sent to the eOLT or a proxy therefor, apprising theeOLT/proxy process of the protocol failure.

OFDM and Other Variants—

It will be appreciated that while the discussion of the exemplaryembodiments of FIGS. 5-8 above are described in terms of a TDMA-basedsystem, the various aspects of the present disclosure can be readilyapplied to other types of systems by those of ordinary skill whenprovided the present disclosure, including those utilizing OFDM(Orthogonal Frequency Division Multiplexing)/OFDMA or other multipleaccess schemes and/or modulation techniques. For example, time-frequencyresources (aka “resource blocks”) within an OFDM/OFDMA system may beused as the basis of access by the various eONUs with respect to thecontrol messages issued by the eOLT (or other data communicationsbetween the entities). Other approaches (whether temporally based, suchas FHSS) or non-temporally based (such as DSSS or even FDMA or the like)can be used consistent with the disclosure as well with properadaptation.

eOLT Apparatus—

FIG. 9 illustrates one exemplary enhanced OLT (eOLT) configurationaccording to the present disclosure. As shown, the eOLT 502 includes: aprocessor (e.g., CPU such as a CISC device or SoC) 902, mass storage903, a memory module 904, an optical network interface 906, and one ormore backend/network interfaces 908. Artisans of ordinary skill in therelated arts will readily appreciate, given the present disclosure, thatthe eOLT 502 may be virtualized and/or distributed within other corenetwork entities, the foregoing apparatus being purely illustrative.

In one exemplary embodiment, the processor 902 may include one or moreof a digital signal processor, microprocessor, field-programmable gatearray, or plurality of processing components mounted on one or moresubstrates. The processor 902 may also comprise an internal cache memory(e.g., L1/L2/L3 cache). The processing subsystem is in communicationwith the mass storage 903 and the memory subsystem 904, the latterincluding memory which may for example comprise SRAM, flash, GDDRx,and/or SDRAM components. The memory subsystem may implement one or moreof DMA type hardware, so as to facilitate data accesses as is well knownin the art. The memory subsystem of the exemplary embodiment comprisesprogram memory that contains computer-executable instructions which areexecutable by the processor subsystem.

A packet or data block buffer or queue 912 is also provided to storeincoming data packets temporarily for before transmission by the opticalinterface 906 to the eONU(s), such as according to FIFO logic (e.g., foruse by the DD function previously described for triggering power-up ofthe laser diode).

The processing apparatus 902 is configured to execute at least onecomputer program stored in memory 904 (e.g., non-transitory computerreadable storage media). The computer program may include a plurality ofcomputer readable instructions configured to, inter alia, generate theaforementioned control messages (e.g., SP_VALUE, SP_DURATION) fortransmission to the eONUs 504 via the optical network interface 906 orthe backend interface(s) 908. In one exemplary embodiment, the protocolstack of the eOLT comprises a MAC layer which communicates with acorresponding MAC layer process on the target eONUs, between which thevarious control messages are communicated, such as according to an IEEEStd 802.3 compliant MPCP or other protocol.

It will be appreciated that while the foregoing discusses software-basedlogic 911 for the eOLT functions described herein, the presentdisclosure contemplates other configurations, including for instance useof firmware/software, use of one or more ASICs (which inherently operatefaster than software-based implementations), and combinations of theforegoing, depending on the attributes of the particular application.

In the exemplary configuration of the eOLT 502 shown, the opticalnetwork (PON) interface comprises a diode-based laser transceiver usingWDM (wave division multiplexing), although other approaches such as DWDMmay be used consistent with the disclosure.

A DSP 910 is also utilized within the architecture of the eOLT 502 tosupport processing of signals for the eOLT including for the opticalinterface(s) 906.

The network and backend interfaces 908 of the eOLT may include forexample any number of wired or wireless PHYs and associated interfaces,such as Ethernet/GbE LAN, WLAN (e.g., 802.11), WMAN (e.g., 802.16), USB,IEEE-1394, or other. These interfaces enable both communication with oneor more controlling or parent processes (e.g., a network controllerwithin the MSO control domain, by which the operation of the eOLT can becontrolled consistent with broader network operational conditions orgoals), as well as non-optical communication with the various eONU 504where needed/provided. As such, the protocol stack of the eOLT mayinclude for instance network/transport layer protocols sufficient fore.g., Internet communication such as TCP/IP, UDP, etc.

eONU Apparatus—

FIG. 10 illustrates one exemplary embodiment of an enhanced ONU (eONU)1000 according to the present disclosure. As shown, the eONU 504includes: a processor (e.g., CPU such as a CISC device or SoC) 1002,mass storage 1003, a memory module 1004, an optical network interface1006, and one or more backend/network interfaces 1008. Artisans ofordinary skill in the related arts will readily appreciate, given thepresent disclosure, that the eONU 504 may be virtualized and/ordistributed within other edge or served premises entities or components,the foregoing apparatus being purely illustrative. For instance, theeONU functionality may be part of a premises modem or even end userdevice such as a PC or server.

In one exemplary embodiment, the processor 1002 may include one or moreof a digital signal processor, microprocessor, field-programmable gatearray, or plurality of processing components mounted on one or moresubstrates. The processor 1002 may also comprise an internal cachememory (e.g., L1/L2/L3 cache). The processing subsystem is incommunication with the mass storage 903 and the memory subsystem 1004,the latter including memory which may for example comprise SRAM, flash,GDDRx, and/or SDRAM components. The memory subsystem may implement oneor more of DMA type hardware, so as to facilitate data accesses as iswell known in the art. The memory subsystem of the exemplary embodimentcomprises program memory that contains computer-executable instructionswhich are executable by the processor subsystem.

A packet or data block buffer or queue 1012 is also provided to storeincoming data packets temporarily for before transmission via theoptical interface 1006 to the eOLT 502, such as according to FIFO logic(e.g., for use by the DD function previously described for triggeringpower-up of the laser diode).

The processing apparatus 1002 is configured to execute at least onecomputer program stored in memory 1004 (e.g., non-transitory computerreadable storage media). The computer program may include a plurality ofcomputer readable instructions configured to, inter alia, receive theaforementioned control messages (e.g., SP_VALUE, SP_DURATION) from theeOLT 502 via the optical network interface 1006 or the backendinterface(s) 1008. In one exemplary embodiment, the protocol stack ofthe eONU comprises a MAC layer which communicates with a correspondingMAC layer process on the cognizant eOLT, between which the variouscontrol messages are communicated, such as according to an 802.3compliant MPCP or other protocol. The eONU logic 1011 is furtherconfigured to un-encapsulate the various fields of the control messagesand extract the SP₁-SP₃/TP data, and duration data as applicable, aswell as the ancillary data (e.g., RF/BF, EN, etc.) and evaluate asdescribed previously herein for possible update to the extant parametersstored in the memory 1004 or mass storage device 1003 of the eONU. Assuch, the eONU logic 1011 is further optionally configured to generatean error message or flag indicating that the eOLT communications havebeen ignored (e.g., due to EN not matching the actual messages receivedor other such condition).

Moreover, the eONU logic 1011 is also configured to implement theappropriate TDMA or other media access protocol(s) for e.g., opticalcommunication with the eOLT MAC.

It will be appreciated that while the foregoing discusses software-basedlogic 1011 for the eONU functions described herein, the presentdisclosure contemplates other configurations, including for instance useof firmware/software, use of one or more ASICs (which inherently operatefaster than software-based implementations), and combinations of theforegoing, depending on the attributes of the particular application.

In the exemplary configuration of the eONU 504 shown, the opticalnetwork (PON) interface comprises a diode-based laser transceiver usingWDM (wave division multiplexing), although other approaches such as DWDMmay be used consistent with the disclosure. OFDM modulation may also beapplied, such that particular time/frequency resource blocks areassigned to the given eONU for communication with the eOLT (therebyproviding multiple access capability for the eOLT). The selectedmultiplexing/modulation technique used in the eONU matches that of thecognizant eOLT, such that the two devices can communicate in the opticaldomain (e.g., during the assigned TDMA time slot, or using theappropriate OFDM time-frequency resource blocks)

A DSP 1010 is also utilized within the architecture of the eONU 504 tosupport processing of signals for the eOLT including for the opticalinterface(s) 1006.

The network and backend interfaces 1008 of the eOLT may include forexample any number of wired or wireless PHYs and associated interfaces,such as Ethernet/GbE LAN, WLAN (e.g., 802.11), WMAN (e.g., 802.16),5G-NR (e.g., 3GPP TS 38.xxx), USB, IEEE-1394, or other. These interfacesenable both communication with one or more downstream or served devices(e.g., at a user's premises; see FIG. 5), as well as non-opticalcommunication with the eOLT 502 where needed/provided. As such, theprotocol stack of the eONU may include for instance network/transportlayer protocols sufficient for e.g., Internet communication such asTCP/IP, UDP, etc., as well as protocols needed to support delivery ofservices to the served premises and networks thereof, the latter whichmay include for instance client devices such DSTBs, gateways, WLAN APs,femtocells (e.g., EUTRAN 4G/4.5G devices), MoCA coaxial wiring, CAT-5/6wiring, and others.

Implementation Example (NG-EPON)-

Referring now to FIG. 11, one exemplary implementation example of theproposed pattern announcement protocol (PPAP) in the context of anNG-EPON system (e.g., one defined under the IEEE P802.3ca project at thedate of this filing) is shown and described in detail. As notedpreviously, the various aspects of the present disclosure can be appliedby one of ordinary skill, given this disclosure, to any number ofdifferent: (i) PON types and protocols; (ii) access schemes (e.g.,TDMA-based, OFDM-based, or even FDMA/WDMA-based), and (iii) PHY media(e.g., optical fiber, differentially signaled twisted pair, etc.),requiring temporal or other synchronization. Hence, the followingexample merely illustrates one such application.

In the example of FIG. 11, all control messages associated with the eONUdiscovery, registration, and upstream channel access arbitration areimplemented using the Multi Point MAC Control (MPCP) protocol (specifiedin IEEE Std 802.3, Clause 64 for 1G-EPON, Clause 77 for 10G-EPON, andClause 144 (under development) for NG-EPON, incorporated herein byreference in its entirety), representing a specialized type of MAControl protocol.

The SP_VALUE message defined herein is, given the size limitation of theMPCP data units (frames) to 64 bytes, and the target size of the datablock of 257 bits, implemented in a new message, with the format 1100shown in FIG. 11. Specifically, the Destination Address field 1102,Source Address field 1104, Length/Type field 1106, Opcode field 1108,FCS field 1110, and Timestamp field 1112 are required by the MPCP dataunit (MPCPDU) structure, and are populated with data accordingly by therespective implementation. The number of bytes 1120 associated with eachfield is shown as well.

The value of Opcode field 1108 is assigned and fixed in one embodiment.For instance, for this SP_VALUE message 1100, the next available Opcodevalue is 0x0018 at the time of writing. Other values are allowed, aslong as the eOLT and eONU implementation agree on the actual Opcodevalue for this control message 1100.

The SpValue field 1116 carries the actual pattern value. In the presentimplementation, a 257-bit long pattern value is selected based on theline code selected for NG-EPON at the time of this writing (256b/257b),but may be readily adapted for other line codes or values. The 257-bitvalue is encoded into 32 bytes as shown, representing bits 1 through 256of the 257-bit long pattern value. Bit 0 is encoded into bit 15 of theSpConfig field 1114, where the SpConfig field is defined as follows:

-   -   Bit 1: SpBalanced flag, representing the Balanced Flag (BF) as        previously defined herein;    -   Bit 2: SpReversed flag, representing the Reversed Flag (RF) as        previously defined herein;    -   Bit 3-4: Spindex value, indicating the type of pattern value        carried in the given SP_VALUE message as previously defined        herein, where a value of “0” indicates SP₁ pattern, a value of        “1” indicates the SP₂ pattern, a value of “2” indicates the SP₃        pattern, and a value of “3” indicates the TP pattern;    -   Bit 5-6: SpCount value, indicating the target number of patterns        announced by the eOLT, as previously defined herein; and    -   Bit 15: SpValue bit 0, completing the 257-bit long pattern        value.        Other bits within the SpConfig field 1114 are reserved, and are        transmitted as “0” (and ignored on reception at the eONU).

As previously noted, the SP_VALUE MPCPDU may be transmitted on abroadcast channel to all eONUs in data communication with the giveneOLT, advantageously providing, inter alia, a simple means of deliveringinitial set of pattern values to all unregistered eONUs. Additionally,this message may be also delivered on a unicast channel to a selectedtarget eONU, such as when specific changes are needed to at least one ofthe pattern values and/or associated pattern configuration to improvethe eONU performance. Multicast to e.g., prescribed subsets of the eONUsmay also be utilized consistent with the SP_VALUE MPCPDU.

The SP_COUNT (i.e., the expression of the generic SP_DURATION messageusing an SP_COUNT parameter; i.e., a number of blocks that aretransmitted for each sequence) for the discovery mode of operation is,in one implementation, encoded into the remaining padding field in theDISCOVERY_GATE MPCPDU (already defined in the current MPCP standard);i.e., an additional 8 octets of the padding zone are assigned to therespective pattern counts as follows:

1. Octet X, X+1: SP₁ pattern count for the discovery operation;

2. Octet X+2, X+3: SP₂ pattern count for the discovery operation;

3. Octet X+4, X+5: SP₃ pattern count for the discovery operation; and

4. Octet X+6, X+7: TP pattern count for the discovery operation.

The starting location within the DISCOVERY_GATE MPCPDU message is in oneimplementation designated with a prescribed value (e.g., marked with“X”), and depends on other factors, such as for example any otherchanges to the DISCOVERY_GATE MPCPDU, such as those that a respectivestandardization project may add to the given control message. In thisexample, the DISCOVERY_GATE MPCPDU is always transmitted on thebroadcast channel (delivered to all connected eONUs), and processed onlyby unregistered eONUs, providing a way to deliver necessary information(e.g., SP_COUNT for the discovery operation) to all unregistered eONUsbefore they are allowed to attempt registration in the system.

In this example, the SP_COUNT for the normal (granting) operational modeis encoded into the remaining padding field in the REGISTER MPCPDU (alsodefined in the current standard); i.e., an additional 8 octets of thepadding zone are assigned to the respective pattern counts as follows:

-   -   1. Octet X, X+1: SP₁ pattern count for the normal (granting)        operation mode;    -   2. Octet X+2, X+3: SP₂ pattern count for the normal (granting)        operation mode;    -   3. Octet X+4, X+5: SP₃ pattern count for the normal (granting)        operation mode; and    -   4. Octet X+6, X+7: TP pattern count for the normal (granting)        operation mode.        The starting location within the REGISTER MPCPDU message is        similarly designated (for instance marked with the        aforementioned “X”), and depends on other factors, such as e.g.,        any other changes to the REGISTER MPCPDU that the respective        standardization project may add to the control message. By        default, the REGISTER MPCPDU in the present example is delivered        to a specific eONU on a unicast logical link, and processed by        the target eONU only, hence advantageously providing a way for        the eOLT to deliver necessary information (e.g., SP_COUNT for        the normal operation mode) to the selected eONU. Additionally,        the REGISTER MPCPDU may be transmitted by the eOLT at any point        of time without causing a change in the state of the eONU        registration, thereby further providing the means to deliver any        updates (e.g., to the SP_COUNT) for the normal operation mode        for the given eONU.

Peer-Based and Other Embodiments

While the exemplary embodiments of the protocol, methods and apparatusdescribed above are generally consistent with a unidirectional controlflow (i.e., eOLT acting as a “master” or “director” and the variouseONUs acting as “agents” or “followers”), the present disclosure alsocontemplates other types of relationships between the various entitieswhen implementing the enhanced discovery, synchronization and operationfunctions described herein, whether in the context of a PONimplementation, or otherwise.

For example, in one alternate configuration, one or more of the eONUs504 may be configured with additional logic such that it can at somelevel participate in as a peer or input source in the parameter (e.g.,SP₁-SP₃ and TP, duration) selection process. For instance, in onevariant, the logic module 1011 of the eONU 504 is configured to transmitdata to the cognizant eOLT 502 (such as via repurposed padding or otherunused data within an extant control/reply message) that may be of useby the eOLT logic 911 in selecting the optimized discovery mode and/oroperational (normal) mode parameters. Such data may include for instancehistorical data on operation of that eONU (e.g., such as where the eONUhas only historically been used very infrequently, and hence may be ableto tolerate settings not tolerated by more frequently used devices onthe PON), data regarding test results for various components of the eONU(e.g., a “weak” or “strong” laser diode as compared to nominal, andhence modification of the AGC pattern/duration to compensate), and/orerror/flag data (e.g., data on the incidence of failures or errors inthe MAC/MPCP protocol or the broader protocol stack in general, therebyindicating general health or reliability of the eONU or componentsthereof). This data reporting may also include data obtained by the eONU504 from proxy or downstream devices within the PON (or served thereby),such as e.g., high data error rates or other operational issuedencountered by downstream devices, or optical power measurements fromother nodes within the PON.

Alternatively or in conjunction with the foregoing data reportingfunctions, the eONU logic 1011 can be configured with additionalintelligence such that it can evaluate the various data it logs orotherwise obtains (e.g., test data, historical operations data, errordata, etc.), and generate recommended values for one or more parameters(or adjustments to the initial parameters set by the eOLT), andcommunicate them to the eOLT such as via a control message protocol orother inter-process (e.g., MAC-MAC) communication. As such, portions ofthe eOLT logic 911 can also be “distributed” or virtualized within othercomponents (including one or more of the eONUs) within the PON.

Moreover, the roles assumed by the eOLT and eONU may vary as a functionof time or operating mode; e.g., wherein in certain operating modes, theeOLT assumes the “master” role, and in other operating modes, the eOLTassumes a “peer” role such that it can receive data and inputs from the“smart” eONU as described above. By virtue of its position within thePON, the eOLT is always cognizant over timing and other multipleaccess-related issues (including TDMA slot and bandwidth allocation);however, it can also be configured to utilize the capabilities of thevarious eONU within the PON for provision of data and enhancedoptimization functions.

It will be recognized that while certain aspects of the disclosure aredescribed in terms of a specific sequence of steps of a method, thesedescriptions are only illustrative of the broader methods of thedisclosure, and may be modified as required by the particularapplication. Certain steps may be rendered unnecessary or optional undercertain circumstances. Additionally, certain steps or functionality maybe added to the disclosed embodiments, or the order of performance oftwo or more steps permuted. All such variations are considered to beencompassed within the disclosure disclosed and claimed herein.

While the above detailed description has shown, described, and pointedout novel features of the disclosure as applied to various embodiments,it will be understood that various omissions, substitutions, and changesin the form and details of the device or process illustrated may be madeby those skilled in the art without departing from the disclosure. Thisdescription is in no way meant to be limiting, but rather should betaken as illustrative of the general principles of the disclosure. Thescope of the disclosure should be determined with reference to theclaims.

It will be further appreciated that while certain steps and aspects ofthe various methods and apparatus described herein may be performed by ahuman being, the disclosed aspects and individual methods and apparatusare generally computerized/computer-implemented. Computerized apparatusand methods are necessary to fully implement these aspects for anynumber of reasons including, without limitation, commercial viability,practicality, and even feasibility (i.e., certain steps/processes simplycannot be performed by a human being in any viable fashion).

What is claimed is:
 1. Computer readable apparatus comprising anon-transitory storage medium, the non-transitory storage mediumcomprising at least one computer program having a plurality ofinstructions, the plurality of instructions configured to, when executedon a digital processing apparatus of a computerized apparatus, cause thecomputerized apparatus to: receive first data related to a firstplurality of synchronization parameters, the first plurality ofsynchronization parameters configured for use in at least two phases ofa synchronization process between the computerized apparatus and acomputerized network apparatus, the at least two phases comprising adiscovery phase and a validation phase; identify second data related toa second plurality of synchronization parameters accessible by thecomputerized apparatus; based at least in part on at least one of (i)the received first data or (ii) the identified second data, causetransmission of third data to the computerized network apparatus via apassive optical network (PON), the third data configured to causeinitiation of the synchronization process; and based at least in part on(i) the received first data and (ii) a determination that an update isneeded, update the second plurality of synchronization parametersaccessible by the computerized apparatus; wherein the update isconfigured to reduce a time required for performance of at least oneprocess associated with the synchronization process.
 2. The computerreadable apparatus of claim 1, wherein the first plurality ofsynchronization parameters comprise prescribed parameters determined,via the computerized network apparatus, based at least on anothersynchronization process between at least one service node of the PON andthe computerized network apparatus.
 3. The computer readable apparatusof claim 1, wherein the plurality of instructions are further configuredto, when executed on the digital processing apparatus, cause thecomputerized apparatus to validate the received first data against oneor more prescribed criteria, the validation (i) comprising aconfirmation of a proper format or length of the first plurality ofsynchronization parameters, the proper format or length being compatiblefor use in the synchronization process, and (ii) performed as part ofthe validation phase.
 4. The computer readable apparatus of claim 3,wherein the one or more prescribed criteria comprise a match between anumber of messages included in the first data and an expected number ofthe messages, the expected number determined by an evaluation of dataincluded in the received first data, the messages configured to beutilized for the synchronization process.
 5. The computer readableapparatus of claim 1, wherein: the PON comprises an Ethernet PON; andthe third data comprises an acknowledgement (ACK) message according toMulti Point Control Protocol (MPCP), the ACK message indicative of aconfirmation of the receipt of the first data.
 6. The computer readableapparatus of claim 1, wherein: the first data comprises a plurality ofcontrol messages from an optical line terminal within the PON; thesecond data comprises at least one prescribed validation criterion; andthe caused transmission of the third data is further based at least on acomparison of a quantity of the plurality of control messages with atleast one aspect of the at least one prescribed validation criterion. 7.Computerized network apparatus for use in a passive optical network(PON), the computerized network apparatus comprising: a PHY (physicallayer) apparatus configured to support optical data communication withat least one service node of the PON; digital processing apparatus indata communication with the PHY apparatus; and storage apparatus in datacommunication with the digital processing apparatus and comprising anon-transitory storage medium, the non-transitory storage mediumcomprising at least one computer program having a plurality ofinstructions, the plurality of instructions configured to, when executedon the digital processing apparatus, cause the computerized networkapparatus to: determine at least two bit patterns for at least onesynchronization parameter, the at least two bit patterns comprising (i)a first bit pattern optimized for performance of a gain controladjustment, and (ii) a second bit pattern optimized for performance of aclock signal recovery, the optimizations relating to a respective timerequired for the performance of the gain control adjustment and theclock signal recovery, the at least one synchronization parameterconfigured for use in a synchronization process between the at least oneservice node and the computerized network apparatus; configure the atleast two bit patterns into at least one protocol data message; andtransmit, via the PHY apparatus, the at least one protocol data messageto the at least one service node.
 8. The computerized network apparatusof claim 7, wherein the synchronization process comprises (i) a firstprocess relating to the gain control adjustment, and (ii) a secondprocess relating to the clock signal recovery.
 9. The computerizednetwork apparatus of claim 7, wherein: the first bit pattern comprises apattern which maximizes a number of data “ls”; and the second bitpattern comprises a pattern which maximizes a number of data valuetransitions of at least one of: (i) from data “0” to data “1”, or (ii)from data “1” to data “0”.
 10. The computerized network apparatus ofclaim 7, further comprising a second PHY apparatus in data communicationwith the digital processing apparatus and configured to support datacommunication with the at least one service node of the PON, and whereinthe plurality of instructions are further configured to, when executedon the digital processing apparatus: receive data relating to an errormessage related to at least a portion of the transmitted at least oneprotocol data message; and based at least on the received data relatingto the error message, re-transmit the at least one protocol datamessage, via the second PHY apparatus, to the at least one service node.11. The computerized network apparatus of claim 7, wherein theperformance of the gain control adjustment occurs during a first definedphase, the first defined phase occurring prior to the performance of theclock signal recovery during a second defined phase distinct from thefirst defined phase.
 12. A computerized method of operating a passiveoptical network (PON), the computerized method comprising: determining aplurality of synchronization parameters to be used during at least twodifferent phases of synchronization between at least one service nodeand a controller node of the PON, the plurality of synchronizationparameters comprising (i) a first bit pattern configured to optimize atleast a first transmit characteristic, and (ii) a second bit patternconfigured to optimize at least a second transmit characteristic; andtransmitting data indicative of at least the first bit pattern and thesecond bit pattern, to the at least one service node via at least oneprotocol data message, the at least one protocol data message configuredto cause the at least one service node to utilize one or more of thefirst bit pattern or the second bit pattern during at least onesubsequent discovery or synchronization process; wherein the one or moreof the first bit pattern or the second bit pattern is configured toreduce a time required for performance of one or more of the at leastone subsequent discovery or synchronization process.
 13. Thecomputerized method of claim 12, wherein the at least two differentphases comprise: (i) a gain phase relating to signal power transmittedby the at least one service node onto the PON; and (ii) a clock signalrecovery phase.
 14. The computerized method of claim 13, wherein the atleast two different phases further comprise a payload phase.
 15. Thecomputerized method of claim 14, wherein the payload phase comprises aphase during which FEC (forward error correction) protected payload datais transmitted, the payload phase delineated by at least two burstdelimiter values.
 16. The computerized method of claim 13, wherein theat least one service node comprises an ONU (optical network unit), andthe controller node comprises an OLT (optical line terminal).
 17. Thecomputerized method of claim 12, wherein the transmitting of the dataindicative of the at least the first bit pattern and the second bitpattern comprises: determining that the at least one service node hasnot transmitted, within a prescribed time period, data representative ofa response to at least a portion of the data indicative of the at leastthe first bit pattern and the second bit pattern, the response relatedto a confirmation of receiving the at least portion of the dataindicative of the at least the first bit pattern and the second bitpattern; and based at least in part on the determining that the at leastone service node has not transmitted the data representative of theresponse, re-transmitting the data indicative of the at least the firstbit pattern and the second bit pattern to the at least one service node.18. The computerized method of claim 17, wherein the re-transmittingcomprises re-transmitting the data indicative of the at least the firstbit pattern and the second bit pattern via at least a second protocoldata message, the at least second protocol data message configured fordata communication according to a second communication protocol which isdifferent from a first communication protocol associated with the atleast one protocol data message; wherein: the first communicationprotocol is utilized for data communication via a first PHY (physicallayer) interface of the at least one service node; and the secondcommunication protocol is utilized for data communication via a secondPHY interface of the at least one service node.
 19. The computerizedmethod of claim 17, wherein the re-transmitting comprises transmitting adifferent number of protocol data messages relative to a number of theat least one protocol data message, the different number of protocoldata messages comprising a varied number of synchronization parametersin at least one of the different number of protocol data messagesrelative to a number of synchronization parameters included in one ormore of the at least one protocol data message.
 20. The computerizedmethod of claim 12, wherein the first bit pattern comprises a bitpattern utilized during an Automatic Gain Control (AGC) period, and thesecond bit pattern comprises a bit pattern utilized during a Clock DataRecovery (CDR) period.